From 83524348531d11f61332d7e8ab0b3acb31498e44 Mon Sep 17 00:00:00 2001
From: rhishikeshj <rhishikeshj@gmail.com>
Date: Mon, 28 Aug 2023 15:42:20 +0200
Subject: [PATCH] Optimise topo-sort.

Avoid creating sets in the recur. This seems to save around 3 seconds for a
graph with about 8k nodes.
---
 src/com/stuartsierra/dependency.cljc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/com/stuartsierra/dependency.cljc b/src/com/stuartsierra/dependency.cljc
index 47a5e7f..6272b5d 100644
--- a/src/com/stuartsierra/dependency.cljc
+++ b/src/com/stuartsierra/dependency.cljc
@@ -143,7 +143,11 @@
                          [add g]))]
         (recur (cons node sorted)
                (remove-node g' node)
-               (clojure.set/union (set more) (set add)))))))
+               ;; NOTE: dep/topo-sort:master creates set from more and add
+               ;; this seems to take much longer than a simple union
+               ;; on more and add.
+               ;; more and add are guaranteed to be sets by the above code.
+               (clojure.set/union more add))))))
 
 (def ^:private max-number
   #?(:clj Long/MAX_VALUE